This invention relates generally to fluid motors, more particularly to a fluid actuated, oscillating reversing motor adapted to provide reciprocatory rotary motion through a portion of a revolution.
Devices of the type are capable of many uses such as closing or opening valves, toggling, camming, clamping, positioning, etc. and the like or performing other services, particularly where "push-pull" or reciprocatory movements are involved. Such actuators usually embody a housing head, a chamber in which a vane is moved first in one direction and then the other to provide a rotary action on a cooperative shaft throughout a portion of a revolution. In such arrangements the vane is impelled to and fro by the pressure of the fluid admitted to one side or the other of the piston or vane within the chamber and with the concurrent exhaust of fluid at the opposite side.
Previous arrangements in such rotary type actuators have required frequent servicing and replacement due to wear, particularly under heavy duty service. More particularly replacement of the sealing means to assure satisfactory operation of the device with a minimum amount of fluid leakage. Prior art arrangements provide a pneumatic system for a leakage rate of 0.1 cubic feet per minute and in some instances the leakage rate is considerably higher.
Various prior art arrangements are available, but in arrangements in pneumatic systems, the pressure required for movement of the shaft is excessive due to friction caused by the sealing arrangement.
One prior art arrangement is shown in U.S. Pat. No. 3,128,679,-Trendle wherein a rotary device is shown having a chamber with a vane and a seal arrangement including an internal seal formed around the inner end of a shaft bore where the shaft passes through the head of the device.
A similar device is shown in U.S. Pat. No. 2,735,406 -Britton. In both arrangements, the shaft seal is located in the bore provided for passage of the power shaft and it has been found that such an arrangment provides a leakage path for the actuating fluid and further increases the moving resistance of the shaft.
Other arrangements for vane type actuators are shown in U.S. Pat. No. 3,131,610-Paulus, wherein a sealarrangement is provided around the entire periphery of the vane and in U.S. Pat. No. 3,179,020 where a split vane is provided with a seal captured between the sections of the vane.
No prior art arrangement is known which provides an actuator having a cylindrical body with head means at each end, where the head means includes openings to rotatably receive the shaft of the actuator where an annular seal is provided on the inner surface of each head to abut an enlarged portion of the shaft and the end of a seal provided around the edge of the vane.
Furthermore, no prior seal is known for use in an actuator device which does not require stiffening or backup support when applied to a vane or stator member in a rotary actuator device to prevent rolling or twisting of the seal under dynamic conditions.